This invention relates to a process for producing glycol diesters. It has been known so far that diacetoxybutenes can be produced by reacting 1,3-butadiene, acetic acid and oxygen or oxygen containing gas in the presence of a palladium catalyst. The diacetoxybutenes thus produced consist of a mixture of various isomers such as of 1,4-diacetoxybutene and 2,4- and 3,4-diacetoxybutenes and are required to be separated from each other since the mixture has only a restricted application as it is. Among the above isomers, 1,4-isomer is a useful substance and can be used for the production of 1,4-butene diol through hydrolysis or dihydrofuran through deacetoxy-cyclization. Alternatively, the 1,4-diacetoxybutene is further hydrogenated into 1,4-diacetoxybutane which can be used for the production of 1,4-butane diol through hydrolysis or tetrahydrofuran through deacetoxy-cyclization. While on the other hand, other isomers have less applications and most of them were only discarded with no effective utilization.
The inventors have made an earnest study on the effective utilization of the isomers other than the 1,4-isomer and, as a result, found that these isomers can be decomposed into acetic acid and butadiene on heating under specific conditions.
More specifically, the inventors have discovered that thermal decomposition of isomers other than 1,4-diacetoxybutene such as 3,4-diacetoxybutene, 1,3-diacetoxybutene and the like, as well as the corresponding diacetoxybutanes which are left after the separation of 1,4-diacetoxybutene or 1,4-diacetoxybutane can easily produce butadiene and/or acetic acid usable as the starting material and have succeeded in the development of the process for producing 1,4-diacetoxybutene or 1,4-diacetoxybutane at a high efficiency by the reuse of the resulting butadiene and/or acetic acid as the starting material for the production of diacetoxybutenes.